/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package edu.usc.irds.sparkler.util;

import java.util.Iterator;
import java.util.function.Function;

/**
 * Transforms a stream of type S to target T
 * @param <S> Source type
 * @param <T> Target type
 */
public class StreamTransformer<S,T> implements Iterator<T> {

    private Iterator<S> source;
    private Function<S,T> transformer;

    /**
     * Creates a transformer
     * @param source iterator of source objects
     * @param transformer transformation function
     */
    public StreamTransformer(Iterator<S> source, Function<S,T> transformer) {
        this.source = source;
        this.transformer = transformer;
    }

    @Override
    public boolean hasNext() {
        return source.hasNext();
    }

    @Override
    public T next() {
        return transformer.apply(source.next());
    }
}
